The present invention relates to a screen display system in an information processing terminal and, more particularly, to a control system for multiwindow display in which a plurality of windows are set in one display screen and data can be independently displayed for every window.
In the information processing terminal equipped with a display device, a rectangular region called a window is set on the display screen, data such as, e.g., characters and the like read out of a data file is displayed in this window, key input operations are executed with reference to the displayed data, and another document is made in another region on the display screen. In what is called a multiwindow system in which a plurality of such windows are set on one display screen, the respective windows are displayed so as to overlap one another while maintaining an arbitrary positional relation. In the case of overlappingly displaying a plurality of windows as mentioned above, hitherto, each side of the overlap windows is used as a parting line and each window is divided into a plurality of rectangular sub-regions and managed, thereby allowing the windows to be displayed in a manner such that a part of the lower window is hidden under the upper window which will be overlapped thereon as disclosed in the JP-A No. 59-102284. If the operator wants to see the data in the hidden region, for example, it is sufficient for the operator to designate the lower window by a cursor and shift the display position thereof, or to change the order with respect to the overlap relation such that the window having the hidden region has the highest display priority.
However, in the conventional multiwindow display device, in the case where the above-mentioned display priority is changed in the state in which another window smaller than one large window was overlappingly displayed in this large window, the small window which has been displayed so far is hidden under the large window, so that the small window completely disappears from the screen. The window which has disappeared from the screen as mentioned above cannot be designated by the cursor. Therefore, such a window cannot be redisplayed on the screen by the ordinary overlap relation changing operation mentioned above. The window which has disappeared can be redisplayed by a special command inputting operation from the keyboard. However, in this case, there is an inconvenience such that the operator must memorize the command format and the overlap order of each window. Consequently, prior to changing the display priority, the operator needs to pay attention to the positional relation among the respective windows and to preliminarily shift the windows which may disappear to safe positions.